The APL Satellite Communications Facility team of (from left) Jim Weber, Bill Dove, Tony Garcia and Jeff Williams was able to contact and gather telemetry from NASA's IMAGE spacecraft, which had been silent for 12 years. The 18-meter (60-foot) antenna they used to track IMAGE is visible through the window and on the background screen.
Credit: APL/Ed Whitman

Back in December 2005, NASA’s Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft went silent, abruptly ending a magnetosphere and aurora research mission that had contributed much to studies of the Sun-Earth connection.

Or so NASA thought. A few weeks ago, after 12 years of silence, IMAGE began talking to Earth again. And the Johns Hopkins Applied Physics Lab’s Satellite Communications Facility has played a lead role in helping the once-lost satellite find its voice.

“We were presented with a rare and unique technical challenge,” said Bill Dove, the Satellite Communications Facility (SCF) manager in the Space Exploration Sector. “Through teamwork and determination, we became the first station to receive data from the long-lost spacecraft.”

Answering the Call

On Jan. 26, after learning that an amateur astronomer may have found IMAGE, mission managers at NASA Goddard Space Flight Center in Greenbelt, Maryland, sought help from several ground stations around the country — including the SCF — to not only locate and track the satellite but also to downlink and store any data it might be transmitting.

This was no simple task. Not only had satellite communications technology changed significantly over the past decade, NASA had previously decommissioned the IMAGE Science and Mission Operations Center. The Goddard team provided what’s known as “nominal sequence of events codes,” the essential files that told the stations how to communicate with the spacecraft. But something was missing — specifically, the last bit of information needed to lock onto IMAGE’s stream of telemetry/housekeeping data.

“For most operating spacecraft, this information is readily available online,” said Tony Garcia, SCF lead engineer in SES. “But IMAGE had been ‘gone’ for so long that the information on its RF [radio-frequency] and telemetry decoding parameters wasn’t readily available.”

The SCF team dialed its large 18-meter (60-foot) dish toward IMAGE’s predicted location and quickly picked up a signal. But the real work came later; Dove spent a few hours configuring the facility’s data-system loggers, and for roughly eight hours over Jan. 29–30, Garcia adjusted the system parameters, fine-tuned the bit rate and electronically “hunted and pecked” for IMAGE until he got a lock on the spacecraft’s telemetry signal at 2:15 p.m. EST on Jan 30.

Telemetry files then began flowing into the SCF computers. Once Dove verified that the files contained actual spacecraft data, he sent them to the NASA team at Goddard — which, in turn, confirmed that the data was indeed from IMAGE.

“It wasn’t easy,” Dove said. “We worked our tails off to achieve telemetry lock. The first tries weren’t successful, but we didn’t give up. Once Tony performed his magic and we locked up, we continued to collect data for hours.”

The SCF team configured the station to conduct autonomous “lights out” contacts and has been receiving a strong signal from IMAGE ever since. As of Feb. 14, the APL station had made contact with the spacecraft 22 more times, collecting and providing NASA with more than 57 hours of IMAGE telemetry data.

NASA has used that data to learn that IMAGE is generally (and surprisingly) healthy. Aside from investigating what caused the decade-long dropout, the IMAGE team will also see if it can do more than just listen to the spacecraft, and talk back to it.

“Establishing the identity of IMAGE and gathering data from the spacecraft has drawn on a wide group of scientists and engineers working together across NASA as well as with our partners,” said Richard Burley, former ground system manager and mission director for IMAGE at Goddard. “We don’t yet know whether we’ll be able to communicate directly to IMAGE, but it’s a fascinating puzzle to try to solve.”

“We love a good technical challenge, and IMAGE gave us a chance to show what incredible things the APL team and facility can do,” Dove added. “If NASA needs our help again, we’re ready to go.”

The Dish on the SCF

The APL Satellite Communications Facility provides nimble flexibility to meet a range of sponsor needs. Both an operational ground station and an experimental platform, the SCF, in just the past five and a half years, has conducted more than 14,000 spacecraft contacts (over 17,000 tracking hours) while supporting more than a dozen independent research and development projects and specialized experiments.

The SCF is one of the oldest operational ground stations in the world. It was established in 1961 to support the world’s first satellite navigation system — Transit, the forerunner to today’s GPS.

The 60-foot dish used to contact IMAGE opened for operations in March 1963. The antenna can command satellites, receive signals and track space probes as far out as 230 million miles from Earth. It has sent commands to and received data from dozens of spacecraft over the decades, including the currently operating Van Allen Probes and TIMED.

The Applied Physics Laboratory, a not-for-profit division of The Johns Hopkins University, meets critical national challenges through the innovative application of science and technology. For more information, visit www.jhuapl.edu.